Lawmaker Retirements to Hit Centrist Ranks

WASHINGTON—A parade of retirements from Congress threatens to deplete Capitol Hill's ranks of centrists, graybeards and legislative craftsmen—increasingly rare commodities in a political hothouse more prone to line-drawing than bridge-building in recent years.

Many of the House members who are leaving are centrist Republicans, which could leave the GOP caucus more dominated than ever by the party's conservative wing. Democrats,...